Vaccination against diseases resulting from pathogenic responses by specific T cell populations

ABSTRACT

The present invention provides vaccines and a means vaccinating a host so as to prevent or control specific T cell medicated proliferative diseases. The vaccine is composed of a pharmaceutically acceptable medium and a segment of the T cell receptor (TCR) present on the surface of the T cells mediating the disease. The vaccine is administered to the host in a manner that induces an immune response directed against the TCR of a pathologic T cell. This immune response down regulates or deletes the pathogenic T cells, thus ablating the disease pathogenesis. Means of determining an appropriate amino acid sequence for such a vaccine are also provided.

This application is a continuation of application Ser. No. 07/987,571filed Dec. 8, 1992, now abandoned, which is a continuation ofapplication Ser. No. 07/382,085 filed Jul. 18, 1989, now abandoned,which is a continuation-in-part of application Ser. No. 07/326,314 filedMar. 21, 1989, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to the immune system and, more specifically, tomethods of modifying pathological immune responses.

Higher organisms are characterized by an immune system which protectsthem against invasion by potentially deleterious substances ormicroorganisms. When a substance, termed an antigen, enters the body,and is recognized as foreign, the immune system mounts both an antibody-mediated response and a cell-mediated response. Cells of the immunesystem, termed B lymphocytes or B cells, produce antibodies whichspecifically recognize and bind to the foreign substance. Otherlymphocytes, termed T lymphocytes or T cells, both effect and regulatethe cell-mediated response resulting eventually in the elimination ofthe antigen.

A variety of T cells are involved in the cell-mediated response. Someinduce particular B cell clones to proliferate and produce antibodiesspecific for the antigen. Others recognize and destroy cells presentingforeign antigens on their surfaces. Certain T cells regulate theresponse by either stimulating or suppressing other cells.

While the normal immune system is closely regulated, aberrations inimmune response are not uncommon. In some instances, the immune systemfunctions inappropriately and reacts to a component of the host as if itwere, in fact, foreign. Such a response results in an autoimmunedisease, in which the host's immune system attacks the host's owntissue. T cells, as the primary regulators of the immune system,directly or indirectly effect such autoimmune pathologies.

Numerous diseases are believed to result from autoimmune mechanisms.Prominent among these are rheumatoid arthritis, systemic lupuserythematosus, multiple sclerosis, Type I diabetes, myasthenia gravisand pemphigus vulgaris. Autoimmune diseases affect millions ofindividuals world-wide and the cost of these diseases, in terms ofactual treatment and expenditures and lost productivity, is measured inbillions of dollars annually. At present, there are no known effectivetreatment for such autoimmune pathologies. Usually, only the symptomscan be treated, while the disease continues to progress, often resultingin severe debilitation or death.

In other instances, lymphocytes replicate inappropriately and withoutcontrol. Such replication results in a cancerous condition known as alymphoma. Where the unregulated lymphocytes are of the T cell type, thetumors are termed T cell lymphomas. As with other malignancies, T celllymphomas are difficult to treat effectively.

Thus there exists a long-felt need for an effective means of curing orameliorating T cell mediated pathologies. Such a treatment shouldideally control the inappropriate T cell response, rather than merelyreducing the symptoms. The present invention satisfies this need andprovides related advantages as well.

SUMMARY OF THE INVENTION

The present invention provides vaccines and a means of vaccinating amammal so as to prevent or control a specific T cell mediatedpathologies. The vaccine is composed of a T cell receptor (TCR) or afragment thereof corresponding to a TCR present on the surface of Tcells mediating the pathology. Alternatively, the vaccine can be apeptide corresponding to sequences of TCRs characteristic of the T cellsmediating said pathology, or anti-idiotypic antibodies which areinternal images of the peptides.

Moreover, the invention provides vaccines for treating the unregulatedreplication of T cells. The vaccine is composed of a TCR or a fragmentthereof corresponding to TCR present on the surface of the unregulated Tcells. Alternatively, the vaccine can be a peptide corresponding tosequences of TCRs characteristic of the unregulated replicating T cells.

Means of determining appropriate amino acid sequences for such vaccinesare also provided. The vaccine is administered to the mammal in a mannerthat induces an immune response directed against the TCR of T cellsmediating the pathology. This immune response down regulates or deletesthe pathogenic T cells, thus ablating the disease pathogenesis.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to vaccines and their use for preventing orameliorating T cell-mediated pathologies, such as autoimmune diseasesand T cell lymphomas. Vaccination provides a specific and sustainedtreatment which avoids problems associated with other potential avenuesof therapy.

As used herein, the term "T cell-mediated pathology" refers to anycondition in which an inappropriate T cell response is a component ofthe pathology. The term is intended to include both diseases directlymediated by T cells and those, such as myasthenia gravis, which arecharacterized primarily by damage resulting from antibody binding, butalso reflect an inappropriate T cell response which contributes to theproduction of those antibodies.

As used herein when referring to the relationship between peptides ofthe invention and sequences of TCRs "corresponding to" means that thepeptide has an amino acid sequence which is sufficiently homologous tothe TCR sequence to stimulate an effective regulatory response need notbe identical to the TCR sequence, however, as shown in Examples II andIII.

The immune system is the primary biological defense of the host (self)against potentially pernicious agents (non-self). These perniciousagents may be pathogens, such as bacteria or viruses, as well asmodified self cells, including virus-infected cells, tumor cells orother abnormal cells of the host. Collectively, these targets of theimmune system are referred to as antigens. The recognition of antigen bythe immune system rapidly mobilizes immune mechanisms to destroy thatantigen, thus preserving the sanctity of the host environment.

The principal manifestations of an antigen-specific immune response arehumoral immunity (antibody mediated) and cellular immunity (cellmediated). Each of these immunological mechanisms are initiated throughthe activation of helper (CD4+) T cells. These CD4+ T cells in turnstimulate B cells, primed for antibody synthesis by antigen binding, toproliferate and secrete antibody. This secreted antibody binds to theantigen and facilitates its destruction by other immune mechanisms.Similarly, CD4+ T cells provide stimulatory signals to cytotoxic (CD8+)T cells which recognize and destroy cellular targets (for example, virusinfected cells of the host). Thus, the activation of CD4+ T cells iscrucial in any attempt to selectively modify immunological function.

T cells owe their antigen specificity to the T cell receptor (TCR) whichis expressed on the cell surface. The TCR is a heterodimericglycoprotein, composed of two polypeptide chains, each with a molecularweight of approximately 45 kD. Two forms of the TCR have beenidentified. One is composed of an a chain and a B chain, while thesecond consists of a gamma chain and a delta chain. Each of these fourTCR polypeptide chains is encoded by a distinct genetic locus containingmultiple discontinuous gene segments. These include variable (V) regiongene segments, joining (J) region gene segments and constant (C) regiongene segments. Beta and delta chains contain an additional elementtermed the diversity (D) gene segment. (Since D segments and elementsare found in only some of the TCR genetic loci, and polypeptides,further references herein to D segments and elements will be inparentheses to indicate the inclusion of these regions only in theappropriate TCR chains. Thus V(D)J refers either to VDJ sequences ofchains which have a D region or refers to VJ sequences of chains lackingD regions.)

During lymphocyte maturation, single V, (D) and J gene segments arerearranged to form a functional gene that determines the amino acidsequence of the TCR expressed by that cell. Since the pool of V, (D) andJ genes which may be rearranged is multi-membered and since individualmembers of these pools may be rearranged in virtually any combination,the complete TCR repertoire is highly diverse and capable ofspecifically recognizing and binding the vast array of antigens to whichan organism may be exposed. However, a particular T cell will have onlyone TCR molecule and that TCR molecule, to a large degree if not singly,determines the antigen specificity of that T cell.

T-Cell Pathologies of Autoimmune Etiology

Animal models have contributed significantly to our understanding of theimmunological mechanisms of autoimmune disease. One such animal model,experimental allergic encephalomyelitis (EAE), is an autoimmune diseaseof the central nervous system that can be induced in mice and rats byimmunization with myelin basic protein (MBP). The disease ischaracterized clinically by paralysis and mild wasting andhistologically by a perivascular mononuclear cell infiltration of thecentral nervous system parenchyma. The disease pathogenesis is mediatedby T cells with specificity for MBP. Multiple clones of MBP-specific Tcells have been isolated from animals suffering from EAE and have beenpropagated in continuous culture. After in vitro stimulation with MBP,these T cell clones rapidly induce EAE when adoptively transferred tohealthy hosts. Importantly, these EAE-inducing T cells are specific, notonly for the same antigen (MBP), but also usually for a single epitopeon that antigen. These observations indicate that discrete populationsof autoaggressive T cells are responsible for the pathogenesis of EAE.

Analysis of the TCRs of EAE-inducing T cells has revealed restrictedheterogeneity in the structure of these disease-associated receptors. Inone analysis of 33 MBP-reactive T cells, only two a chain V region genesegments and a single α chain J region gene segment were utilized.Similar restriction of β chain TCR gene usage was also observed in thisT cell population. Only two β chain V region segments and two J regiongene segments were found. More importantly, approximately eighty percentof the T cell clones had identical amino acid sequences across theregion of β chain V-D-J joining. These findings confirm the notion ofcommon TCR structure among T cells with similar antigen specificitiesand indicate that the TCR is an effective target for immunotherapeuticstrategies aimed at eliminating the pathogenesis of EAE.

Various attempts have been made to exploit the antigen specificity ofthe autoaggressive T cells in devising treatment strategies for EAE. Forexample, passive administration of monoclonal antibodies specific forTCRs present on EAE-inducing T cells has been employed. In the mousemodel of EAE, infusion of a monoclonal antibody specific for V.sub.β 8,the major β chain V region gene used by MBP-specific T cells, reducedthe susceptibility of mice to subsequent EAE induction (Acha-Orbea etal., Cell 54:263-273 (1988) and Urban et al., Cell 54:577-592 (1988)).Similar protection has been demonstrated in rat EAE with a monoclonalantibody reactive with an unidentified idiotypic determinant of the TCRon MBP specific T cells (Burns et al., J. Exp. Med. 169:27-39 (1989)).While passive antibody therapy appears to have some ameliorative effecton EAE susceptibility, it is fraught with potential problems. Theprotection afforded is transient, thus requiring repeated administrationof the antibody. Multiple infusions of antibody increases the chancesthat the host will mount an immune response to the administeredantibody, particularly if it is raised in a xenogeneic animal. Furtheran antibody response to a pathogenic T cell clone represents only oneelement in the complete immune response and neglects the potentialcontributions of cellular immunity in resolving the autoreactivity.

The role of cellular immunity in reducing the activity of autoaggressiveT cells in EAE has been examined and potential therapies suggested. In amanner similar to the passive antibody approach, regulatory T cells havebeen derived ex vivo and readministered for immunotherapy. For example,Sun et al., Nature, 332:843-845 (1988), have recently isolated a CD8+ Tcell clone from convalescing rats in whom EAE had been induced byadoptive transfer of an MBP-specific CD4+ T cell line. This CD8+ T cellclone displayed cytolytic activity in vitro for the CD4+ T cell used toinduce disease. Moreover, adoptive transfer of this CTL clone reducedthe susceptibility of recipient rats to subsequent challenge with MBP.Lider, et al., (Science, 239:181-183 (1988)) have also isolated a CD8+ Tcell clone with suppressive activity for EAE-inducing T cells. This CD8+clone was isolated from rats vaccinated with attenuated disease-inducingT cell clones and, though it showed no cytolytic activity in vitro, itcould suppress MBP-driven proliferation of EAE-inducing T cells.Although these studies indicate that the CD8+ T cells could downregulateEAE, it is hard to reconcile a major role for these selected CD8+ CTLsin the long-term resistance of recovered rats since Sedgwick, et al.,(Eur. J. Immunol., 18:495-502 (1988)) have clearly shown that depletionof CD8+ cells with monoclonal antibodies does not affect the diseaseprocess or recovery.

In the experiments of Sun et al., and Lider et al., described above, theadministration of extant derived regulatory T cells overcomes the majorobstacle of passive antibody therapy; it permits a regulatory responsein vivo of prolonged duration. However, it requires in vitro cultivationwith attenuated disease-inducing T cells to develop clones of suchregulatory T cells, a costly and labor intensive process. Further, in anoutbred population such as humans, MHC non-identity among individualsmakes this a highly individualized therapeutic strategy. Regulatoryclones need to be derived for each individual patient and thenre-administered only to that patient to avoid potential graft versushost reactions.

Direct vaccination with attenuated disease-inducing T cell clones alsohas been employed as a therapy for EAE. MBP-specific T cells, capable oftransferring disease, have been attenuated by gamma irradiation orchemical fixation and used to vaccinate naive rats. In some cases,vaccinated animals exhibited resistance to subsequent attempts at EAEinduction (Lider et al., supra; see Cohen and Weiner, Immunol. Today9:332-335 (1988) for review). The effectiveness of such vaccinations,however, is inconsistent and the degree of protection is highlyvariable. T cells contain a multitude of different antigens which inducean immune response when the whole T cell is administered as a vaccine.This phenomenon has been demonstrated by Offner et al., (J.Neuroimmunol., 21:13-22 (1989)), who showed that immunization with wholeT cells increased the delayed type hypersensitivity (DTH) response asmeasured by ear swelling to those T cells in an incremental manner asthe number of vaccinations increased. However, positive DTH responseswere found in both protected and non-protected animals. Rats respondedsimilarly to both the vaccinating encephalitogenic T cells and control Tcells. Conversely, vaccination with PPD-specific T cells from aPPD-specific T cell line induced DTH to the vaccinating cells as well asto an encephalitogenic clone even though no protection was observed. Thesimilar response of vaccinated rats to both disease-inducing and controlcells, as quantified by delayed-type hypersensitivity (a measure ofcell-mediated immunity), indicates that numerous antigens on these Tcells are inducing immune responses. Thus, vaccination with attenuateddisease-inducing T cells suffers from a lack of specificity for theprotective antigen on the surface of that T cell, as well as, variableinduction of immunity to that antigen. As a candidate for the treatmentof human disease, vaccination with attenuated T cells is plagued by thesame labor intensiveness and need for individualized therapies as notedabove for infusion of CD8+ cells.

The present invention provides an effective method of immunotherapy forT cell mediated pathologies, including autoimmune diseases, which avoidsmany of the problems associated with the previously suggested methods oftreatment. By vaccinating, rather than passively administeringheterologous antibodies, the host's own immune system is mobilized tosuppress the autoaggressive T cells. Thus, the suppression is persistentand may involve any and all immunological mechanisms in effecting thatsuppression. This multi-faceted response is more effective than theuni-dimensional antibodies or extant-derived regulatory T cell clones.

As they relate to autoimmune disease, the vaccines of the presentinvention comprise TCRs of T cells that mediate autoimmune diseases. Thevaccines can be whole TCRs substantially purified from T cell clones,individual T cell receptor chains (for example, α, β, etc.) or portionsof such chains, either alone or in combination. The vaccine can behomogenous, for example, a single peptide, or can be composed of morethan one peptide, each of which corresponds to a portion of the TCR. By"substantially pure" it is meant that the TCR is substantially free ofother biochemical moieties with which it is normally associated innature. Alternatively, the vaccines comprise peptides of varying lengthscorresponding to the TCR or portions thereof. The peptides can beproduced synthetically or recombinantly, by means well known to thoseskilled in the art. Preferably, the peptide vaccines correspond toregions of the TCR which distinguish that TCR from other nonpathogenicTCRs. Such specific regions are preferably located within the Vregion(s) of the respective TCR polypeptide chains. Most preferably, thepeptide corresponds to a short sequence spanning the V(D)J junction,thus restricting the immune response solely to those T cells bearingthis single determinant.

The vaccines are administered to a host exhibiting or at risk ofexhibiting an autoimmune response. Definite clinical diagnosis of aparticular autoimmune disease warrants the administration of therelevant disease-specific TCR vaccines. Prophylactic applications arewarranted in diseases where the autoimmune mechanisms precede the onsetof overt clinical disease (for example, Type I Diabetes). Thus,individuals with familial history of disease and predicted to be at riskby reliable prognostic indicators could be treated prophylactically tointerdict autoimmune mechanisms prior to their onset.

TCR vaccines can be administered in many possible formulations, inpharmacologically acceptable mediums. In the case of a short-peptide,the peptide can be conjugated to a carrier, such as KLH, in order toincrease its immunogenicity. The vaccine can be administered inconjunction with an adjuvant, various of whihc are known to thoseskilled in the art. After an initial immunization with the vaccine, abooster can be provided. The vaccines are administered by conventionalmethods, in dosages which are sufficient to elicit an immunologicalresponse, which can be easily determined by those skilled in the art.

Appropriate peptides to be used for immunization can be determined asfollows. Disease-inducing T cell clones reactive with the targetantigens are isolated from affected individuals. Such T cells areobtained from site of active autoaggressive activity such as a lesion inthe case of pemphigus vulgaris, CNS in the case of multiple sclerosis ormyasthenia gravis or synovial fluid or tissue in the case of rheumatoidarthritis. The TCR genes from these autoaggressive T cells are thensequenced. Polypeptides corresponding to TCRs or portions thereof thatare selectively represented among disease inducing T cells (relative tonon-pathogenic T cells) can then be selected as vaccines, and made andused as described above.

T Cell Pathologies of Malignant Etiology

To illustrate the utility of TCR vaccination, autoimmune disease hasbeen discussed. However, T cell lymphoma is another T cell pathologywhich would be amenable to this type of treatment. Application of thistechnology in the treatment of T lymphoma would be conducted invirtually identical fashion. In one important respect, however, thistechnology is more readily applied to T cell proliferative disease sincethe isolation of the pathogenic T cells is more easily accomplished.Once the clones are isolated the technology is applied in the mannerdescribed above. Specifically, the TCR genes of the T lymphoma aresequenced, appropriate regions of those TCRs are identified and used asvaccines. The vaccines can comprise single or multiple peptides, and canbe administered in formulations with or without adjuvants byconventional means.

The following examples are intended to illustrate but not limit theinvention.

EXAMPLE I Rat Model of EAE

Female Lewis rats, (Charles River Laboratories, Raleigh-Durham, N.C.),were immunized in each hind foot pad with 50 μg of guinea pig myelinbasic protein emulsified in complete Freund's adjuvant. The first signsof disease were typically observed 9 to 11 days post-immunization.Disease severity was scored on a three point scale as follows: 1=limptail; 2=hind leg weakness; 3=hind leg paralysis. Following a diseasecourse of approximately four to six days, most rats spontaneouslyrecovered and were refractory to subsequent EAE induction.

EXAMPLE II Selection and Preparation of Vaccines

Vaccinations were conducted with a T cell receptor peptide whosesequence was deduced from the DNA sequence of a T cell receptor B chaingene predominating among EAE-inducing T cells of SJ/L mice. The DNAsequence was that reported by Urban, et al., supra, which isincorporated herein by reference. A nine amino acid peptide, having thesequence of VDJ junction of the TCR β chain of the mouse, wassynthesized by methods known to those skilled in the art. The sequenceof this peptide is: SGDAGGGYE. (Amino acids are represented by theconventional single letter codes.) The equivalent sequence in the rathas been reported to be: SSD-SSNTE (Burns et al., J. Exp. Med. 169:27-39(1989)). The peptide was desalted by Sephadex G-25 (Pharmacia FineChemicals, Piscataway, N.J.) column chromatography in 0.1M acetic acidand the solvent was subsequently removed by two cycles oflyophilization. A portion of the peptide was conjugated to keyholelimpet hemocyanin (KLH) with glutaraldehyde at a ratio of 7.5 mgs ofpeptide per mg of KLH. The resulting conjugate was dialyzed againstphosphate buffered saline (PBS).

EXAMPLE III Vaccination against EAE

Vaccines used in these studies consisted of free VDJ peptide and also ofVDJ peptide conjugated to KLH. These were dissolved in PBS and wereemulsified with equal volumes of either (1) incomplete Freund's adjuvant(IFA) or (2) complete Freund's adjuvant (CFA), made by suspending 10mg/ml heat-killed desiccated Mycobacterium tuberculosis H37ra (DifcoLaboratories, Detroit, Mich.) in IFA. Emulsions were administered to8-10 week old female Lewis rats in a final volume of 100 microliters perrat (50 microliters in each of the hind footpads). 5 μg of unconjugatedVDJ peptide were administered per rat. KLH-VDJ conjugate wasadministered at a dose equivalent to 10 μg of KLH per rat. Twenty-ninedays later each rat was challenged with 50 μg of guinea pig myelin basicprotein in complete Freund's adjuvant in the front footpads. Animalswere monitored daily beginning at day 9 for clinical signs of EAE andwere scored as described above. The results are presented in Table I. Ascan be seen, not only was there a reduced incidence of the disease inthe vaccinated individuals, but in those which did contract the disease,the severity of the disease was reduced and/or the onset was delayed.The extent of protection varied with the vaccine formulation, thoseincluding CFA as the adjuvant demonstrating the greatest degree ofprotection.

                  TABLE I    ______________________________________    Animal          Vaccination  Days After Challenge    No.   (Adjuvant)   10    11  12  13  14  15  16  17  18    ______________________________________    1     VDJ (IFA)    --    --  2   3   3   3   --  --  --    2     "            --    --  1   3   3   3   2   --  --    3     "            --    --  --  3   3   3   2   --  --    4     VDJ (CFA)    --    --  --  --  1   1   1   --  --    5     "            --    --  --  --  --  --  --  --  --    6     "            --    --  --  1   3   3   3   2   --    7     KLH-VDJ (CFA)                       --    --  --  1   3   2   --  --  --    8     "            --    --  --  --  1   1   1   1   --    9     "            --    --  --  --  --  --  --  --  --    10    KLH-VDJ (IFA)                       --    1   3   3   2   2   1   --  --    11    "            --    --  3   3   3   3   3   2   --    12    "            --    --  1   3   3   3   3   --  --    13    NONE         1     3   3   3   3   1   --  --  --    14    "            --    1   3   3   3   1   --  --  --    15    "            1     3   3   3   1   --  --  --  --    ______________________________________     Scoring:     -- no signs     1) limp tail     2) hind leg weakness     3) hind leg paralysis

EXAMPLE IV

Vaccination against EAE with Lewis Rat VDJ Peptides

The VDJ peptide used in the previous examples was synthesized accordingto the sequence of TCR β chain molecules found on EAE-inducing T cellsin B10.PL mice. In addition, peptides were synthesized and tested whichcorrespond to sequences found on encephalitogenic T cells in Lewis rats.These VDJ sequences are homologous with that of B10.PL mice, but notidentical. The rat peptides were synthesized according to the DNAsequences reported by Burns, et al. and Chluba, et al., Eur. J. Immunol.19:279-284 (1989). The sequences of these three peptides designated IR1,2 and 3, are shown below, aligned with the B10.PL mouse sequence used inExamples I through III (VDJ). ##STR1##

The preparation, administration and evaluation of these vaccines wereconducted as described in Examples I through III with the followingexceptions: 50 μg of the individual VDJ peptides were incorporated intovaccine formulations containing CFA; neither vaccinations in IFA norvaccinations with peptides conjugated to KLH were conducted. Controlanimals were untreated prior to MBP challenge as in Example III or werevaccinated with emulsions of PBS and CFA to assess the protective effectof adjuvant alone. The results are shown in Table II below.

                  TABLE II    ______________________________________    Animal          Vaccination  Days After Challenge    No.   (Adjuvant)   10    11  12  13  14  15  16  17  18    ______________________________________    1     None         --    1   2   3   3   2   --  --  --    2     "            1     3   3   3   2   --  --  --  --    3     "            --    2   3   3   3   1   --  --  --    4     PBS-CFA      1     2   3   3   3   --  --  --  --    5     "            1     2   3   3   3   --  --  --  --    6     "            --    2   3   3   3   --  --  --  --    7     IR1 (50 μg)                       --    --  --  2   1   --  --  --  --    8     "            --    --  --  --  1   3   --  --  --    9     "            --    --  --  1   1   1   1   --  --    10    IR2 (50 μg)                       --    --  1   3   3   3   --  --  --    11    "            --    --  --  --  2   2   3   3   --    12    "            --    --  --  --  1   --  --  --  --    13    IR3 (50 μg)                       1     3   3   3   2   --  --  --  --    14    "            --    --  2   3   3   --  --  --  --    15    "            --    --  --  --  --  --  --  --  --    ______________________________________     Scoring:     -- no signs     1) limp tail     2) hind leg weakness     3) hind leg paralysis

As shown in Table II, disease in unvaccinated control animals wasobserved as early as day 10. Disease was characterized by severeparalysis and wasting, persisted for 4 to 6 days and spontaneouslyremitted. PBS-CFA vaccinated rats displayed disease courses virtuallyindistinguishable from those of unvaccinated controls. In contrast,delays in onset were observed in some of the IR1, 2 or 3 vaccinatedanimals and others showed both delayed onset as well as decreasedseverity and/or duration of disease. Overall, however, vaccinations withthe rat VDJ peptides (IR1-3) were slightly less effective than thosewith the mouse VDJ peptide (Example III).

EXAMPLE V Vaccination with V Region Specific Peptides

A peptide specific for the V β 8 gene family was tested as a vaccineagainst EAE. V β 8 is the most common β chain gene family used byencephalitogenic T cells in both rats and mice. A peptide wassynthesized based on a unique DNA sequence found in the V β 8 gene, andwhich is not found among other rat V β genes whose sequences werereported by Morris, et al., Immunogenetics 27:174-179 (1988). Thesequence of this V β 8 peptide, designated IR7, is:

    IR7 D M G H G L R L I H Y S Y D V N B T E K

The efficacy of this V β 8 peptide was tested in the Lewis rat model ofEAE (Example I) as described in Examples II and III. 50 μg of peptidewere tested in CFA. Vaccinations in IFA or with peptide-KLH conjugateswere not conducted. The results of these studies are shown in Table III.

                  TABLE III    ______________________________________    Animal          Vaccination  Days After Challenge    No.   (Adjuvant)   10    11  12  13  14  15  16  17  18    ______________________________________    1     IR7 (50 μg)                       --    --  1   2   3   3   3   --  --    2     "            --    --  --  --  1   1   --  --  --    3     "            --    --  --  --  --  --  --  --  --    ______________________________________     Scoring:     -- no signs     1) limp tail     2) hind leg weakness     3) hind leg paralysis

The results of vaccinations conducted with the rat V β 8 peptide aresimilar to those observed with the mouse and rat VDJ peptides. Delayedonset as well as decreased severity and duration of disease was observedin one animal. One animal was completely protected.

EXAMPLE VI Vaccination with J Region Peptides

A peptide was synthesized which corresponds to the J α gene segment,TA39, found among both rat and mouse encephalitogenic T cell receptors.The sequence of this peptide, designated IR5, is:

    IR5 R F G A G T R L T V K

The efficacy of the JαTA39 peptide was tested in the Lewis rat model ofEAE (Example I) as described in Examples II and III. 50 μg of peptidewere tested in CFA. Vaccinations in IFA or with peptide-KLH conjugateswere not conducted. The results of these studies are shown in Table IV.

                  TABLE IV    ______________________________________          Vaccin-    Animal          ation    Days After challenge    No.   (Adjuvant)                   10    11  12  13  14  15  16  17  18  19                                 20    ______________________________________    1     IR5      --    --  --  --  --  2   1   1   1   1                                 --                                  (50 μg)                                 2 IR5 -- -- -- -- -- -- -- -- -- -- --                                  (50 μg)                                 3 IR5 -- -- -- -- -- -- -- -- -- -- --                                  (50 μg)    ______________________________________     Scoring:     -- no signs     1) limp tail     2) hind leg weakness     3) hind leg paralysis

The results of vaccinations conducted with the rat J a TA39 peptide aremore effective than those observed with the mouse and rat VDJ peptidesor the V β 8 peptide. Two of three animals were totally protected and,in the third, disease onset was markedly delayed. Severity was alsoreduced in this animal though disease persisted for a normal course of 5days. Importantly, the two animals which were completely protectedshowed no histologic evidence of T cell infiltration of the CNS. Thisresult indicates the vaccinating with the J.sub.α TA39 very efficientlyinduces a regulatory response directed at encephalitogenic T cells. Evensub-clinical signs of disease were abrogated.

EXAMPLE VII Vaccination with mixtures of TCR Peptides

Vaccinations were conducted with a mixture of TCR peptides. This mixturecontained 50 μg of each of the peptides IR1, 2, 3 and 5 (the three ratVDJ peptides and the rat JαTA39 peptide).

The efficacy of this peptide mixture was tested in the Lewis rat model(Example I) as described in Examples II and III. Peptides were tested inCFA. Vaccinations in IFA or with peptide-KLH conjugates were notconducted. The results of these studies are shown in Table V.

                  TABLE V    ______________________________________    Animal          Vaccination  Days After Challenge    No.   (Adjuvant)   10    11  12  13  14  15  16  17  18    ______________________________________    4     IR1, 2, 3, 5 --    --  --  --  --  --  --  --  --    5     (50 μg each)                       --    --  --  --  --  --  --  --  --    6     "            --    --  --  --  --  --  --  --  --    ______________________________________     Scoring:     -- no signs     1) limp tail     2) hind leg weakness     3) hind leg paralysis

The results of vaccinations conducted with the rat JαTA39 and three VDJpeptides are more effective than any described in the previous examples.All three animals were totally protected. In addition to the absence ofany clinical signs of EAE, two of these three animals were completelyfree of histological evidence of T cell infiltration into the CNS whilethe third showed only two small foci of lymphocytic infiltration at thebase of the spinal cord.

Although the invention has been described with reference to thepresently-preferred embodiment, it should be understood that variousmodifications can be made without departing from the spirit of theinvention. Accordingly, the invention is limited only by the followingclaims.

We claim:
 1. A composition for reducing the severity of a T cellproliferative disease mediated by unregulated T cell replication of Tcells having restricted T cell receptor heterogeneity in a mammalcomprising (1) a pharmaceutically acceptable medium and (2) asubstantially pure, immunogenic single chain peptide having an aminoacid sequence of a non-constant region of a T cell receptor (TCR)polypeptide chain present on the surface of said T cells, wherein saidcomposition induces an immune response against said unregulated T cellsthat reduces the severity of said disease.
 2. The composition of claim1, wherein said peptide has an amino acid sequence derived from avariable region sequence of a T cell receptor polypeptide chain.
 3. Thecomposition of claim 1, wherein said peptide has an amino acid sequencederived from the V(D)J junction of a T cell receptor polypeptide chain.4. The composition of claim 1, comprising more than one substantiallypure, immunogenic single chain peptide derived from the non-constantregions of different T cell receptor polypeptide chains.
 5. A method ofreducing the severity of a T cell proliferative disease mediated byunregulated T cell clonal replication of T cells having restricted Tcell receptor heterogeneity in a mammal, comprising administering thecomposition of claim
 1. 6. The method of claim 5, wherein saidcomposition is conjugated to a carrier.
 7. The method of claim 5,wherein said composition is administered more than once.
 8. The methodof claim 5, wherein said composition is administered in conjunction withan adjuvant.
 9. A method of selecting a composition for use in reducingthe severity of a T cell proliferative disease mediated by unregulated Tcell clonal replication of T cells having restricted T cell receptor(TCR) heterogeneity in a mammal comprising the steps of:a. Obtaining aclone of T cells mediating said T cell proliferative disease; b.Determining the amino acid sequence of non-constant regions of TCRs fromsaid obtained T cell clone. c. Selecting segments of said amino acidsequence of said TCRs from said T cells meditating said T cellproliferative disease, and d. Synthesizing or selecting an amino acidsequence of said selected segments or functional equivalents thereofthat reduces the severity of said T cell proliferative disease.